The invention relates to motor-driven stair climbing devices for conveying equipment and goods, in particular wheelchairs with handicapped persons, in connection with which the wheelchair is attached removably to the stair climber, according to the introductory clause of claim 1.
Motor-driven stair climbing devices are known. Two construction principles are widely known for conveying wheelchairs with handicapped persons. One construction principle uses numerous wheels that rotate not only around their own axle but at the same time around an axle shared by all wheels. Cf. DE-C 37 13 564 or DE-C 32 26 294. On these devices, on the one hand it is advantageous that only rubber-tired wheels come into contact with the stairway and particularly the edge of the stairs, such that damage is largely ruled out; on the other hand, it is very dangerous that the wheels can only engage the steps to a limited depth. Operating these devices thus requires special cautious and circumspection, last but not least because the load consists of a person. In reality, however, stairways come in many designs: they range from relatively flat stairways running completely straight to narrow, steep winding stairways. Climbing stairways with stair climbers based on the multiple-wheel principle is not risk-free, because the apparatus can tilt over. The stair climber, the wheelchair and the person therefore have to be kept balanced by a strong operator.
The second widely known principle of construction uses two parallel crawlers. The crawlers are long enough that at least three stairs can be grasped at the same time. Accidental tipping over of the wheelchair and the person is thus no longer possible, thus eliminating falls with resulting injuries or even cases of death. Because of the length of the crawlers, however, these stair climbers have problems moving on narrow and curved stairways.
Finally, a stair climbing device has already been proposed that works with a spider-like leg system. However, such a device requires a highly complicated system of touch and position sensors and corresponding actuators that can only be controlled by means of a highly complex computer program in order to prevent the occurrence of missteps or dangerous inclinations of the platform carrying the wheelchair. A practical implementation of this spider leg principle is not yet known.
The present invention is based on the technical problem of indicating a stair climbing device of the type mentioned in the beginning that is not only so light and space-saving that it can be attached removably to any desired goods to be conveyed and in particular to wheelchairs, but also offers a particularly high degree of safety.
This technical problem is solved by a stair climbing device with the features of claim 1.
Thanks to the present invention, the stair climber always stands on two steps, namely either on the next steps or, if the stairway is not too narrow or too winding, on the steps after the next ones. The person operating the stair climber is thereby relieved as much as possible in terms of force; henceforth he/she only has guiding and steering tasks. Using the construction principle according to the invention, it would even be possible to build operator-free stair climbers.
A further advantage is that the support device can be built relatively short because it only needs to bridge over one or two stairs. Since it can also be built very narrow, narrowly winding stairways do not pose problems either.
According to an advantageous design of the invention, the support device is attached to the stair climber. In this way the object conveyed, in particular the wheelchair, remains unmodified.
According to a first design of the invention, the support device executes a linear lift movement. Linearly moving support devices can be one or more telescoping feet or also one or more scissor legs.
This action is comparable to a healthy person""s climbing of stairs.
If the support device is designed advantageously in such a way that it can execute a swinging movement, in addition to the linear lift movement if necessary, this results in considerably greater flexibility with regard to the stairs to be climbed.
According to a first variant of this, a mounting system is provided on the stair climber or on the wheelchair; it is equipped with a hinge pin on which the support device is mounted swiveling. Provided between the support device and the mounting device is a braking and blocking device that is controlled by a sensor in such a way that it blocks the support device as soon as the stair climber threatens to topple over the stairway, and releases the support device as long as the stair climber is properly inclined relative to the stairway.
With this construction, under normal circumstances the support device is fully and freely movable relative to the stair climbing device or the object conveyed. In this way, it can be freely adapted to stairways of any steepness or flatness. Flat landings do not cause difficulties either. For conveying on level surfaces, the support device can even be-folded up under the object conveyed, in particular the wheelchair. Only when the stair climber device takes up a position such that there is a danger of tilting over is the hinge of the support device blocked, namely until the operator has brought the stair climbing device back into a safe position.
Devices, preferably support feet made of an elastic, stairway-protecting material attached in the lower end area of the support device, advantageously provide a support action impacting largely vertically on the stepping surface of one of the next steps down when the swinging motion is blocked. It has been shown that the support on the stepping surface of the stairs is far safer and more reliable than support on the front edge of the stairs. The jolt caused when the hinge is blocked is thus optimally intercepted.
As an alternative to this, a continuous creeper band is attached at the free end of the support device. This creeper band is short enough that it only needs to bridge over two stairs. Also, only a single, narrow creeper band is needed in the middle of the stairway so that curve-negotiating characteristics are ensured.
According to a third variant, a turnstile with at least two, preferably three support wheels is attached at the free end of the support device. Constructions of a turnstile and support wheels are already used in stair climbing devices.
According to a fourth variant, a paternoster-like lift mechanism is attached to the support device.
According to an advantageous further development of the invention, there is the possibility for the foot or scissor leg executing a linear lift movement, the creeper belt, the turnstile or the paternoster to be motor-driven, preferably synchronized with the lift mechanism of the stair climber itself. In this case, the object conveyed, in particular the wheelchair, is conveyed up and down the stairs with only minimal vibrations. The operator henceforth only has a guiding function and no longer a holding function. Such stair climbers can thus be operated by less powerful persons. The constantly active braking and blocking system prevents the stair climber from tipping over with the wheelchair and the handicapped person in case of a danger.
According to a first variant, the braking and blocking system consists of a ratchet wheel and a ratchet as a heeling sensor. In this connection, the center of the ratchet wheel is preferably situated in the center of the hinge pin and the ratchet is designed as a pendulum and mounted swinging on the mounting device. As soon as the stair climber tips forward, the ratchet engages the teeth of the ratchet wheel and blocks the hinge. Such a blocking system is mechanically simple and operationally reliable.
In this regard, the ratchet advantageously consists of a low-mass part that quickly engages the ratchet wheel due to its low mass, and a high-mass part that is responsible for maintaining the vertical direction under the action of gravity. Both parts are held together by a spring which, however, is weak enough that it does not delay the ratchet""s rapid engaging in the ratchet wheel.
In this regard, the angle of the ratchet wheel relative to the support device is advantageously adjustable. Shifting of the overall center of gravity brought about by the different dimensions and weights of the stair climber, the wheelchair and the handicapped person are thereby balanced out.
Another variant of the braking and blocking system consists of a lockable tension bar of finite length between the support arm on the one hand and the mounting device or stair climber on the other hand.
According to a third variant, a shoe brake is provided as the braking and blocking system.
According to a fourth variant, a spring band brake is provided as the braking and blocking system. These brakes operate very quickly and reliably and already have the necessary free-wheeling operation.
An electrical coupling or a shoe brake is also suitable.
According to another variant, the braking and blocking system is designed as a lockable cylinder piston unit. This is preferably a cylinder piston unit with an internal fluid circuit and, in the fluid circuit, a check valve controlled by the heeling sensor. Hydraulic oils as well as gases can be considered for the fluid.
According to an advantageous further development of the invention, there is a support spring between the support arm and the mounting plate or stair climber. This support spring must be designed in such a way that it is powerless when the stair climbing device is in the properly inclined position relative to the stairway. If the stair climber leans backward toward the stairway, the spring presses it back into the normal position. If the stair climber tends to tilt dangerously forward, the spring draws it back into the correct position. The support spring thereby relieves the operator""s strength in both cases.
To further relieve the operator and to also be able to convey heavy loads quickly and, above all, safely over the stairway, a drive is provided parallel to the braking and blocking system. This can be an electric motor with gears, a hydraulic cylinder, an electric cylinder or the like. In each case, the drive is controlled contingent upon the differences between the desired values and actual values of the position of the support device relative to the stair climber and/or of the pressure forces of the support device on the stairway.
It is clear that considerable space and weight can be spared if, according to a further development, the drive is integrated into the braking and blocking system.
Several variants of construction are also possible for the lift mechanism of the stair climber itself.
According to a first variant, the lift mechanism essentially comprises a straight-line mechanism, a lifting frame mounted movably on it and at least one flap mounted on the lift frame and able to be swung in and out. A continuous chain with a push lever between the chain and the flap is provided as the drive source for the flap. Support feet of a nonskid, stairway-protecting material on the lower edge of the flap complete the construction.
An electric motor with gears is preferably suitable as the drive source.
According to a second variant, the lift mechanism essentially comprises two continuous chains circling parallel and in paternoster-like manner, at least one foot element on each chain and an electric motor with gears as the drive source, and the foot elements stand on the stairway. Such a construction requires relatively little power, and this clearly relieves the source of electric power carried on the stair climber. There is only little load on the material, such that the overall construction can be designed particularly easily.
The foot elements preferably stand with a rounded edge on the stairway. If the foot elements also have a nonskid, abrasion-proof coating, optimal conditions are obtained.
Safety is obviously optimal when the stair climber is drawn as far as possible into the stair. To ensure this, feelers in the form of contact bars are attached on the rear of the stair climber on the right and left; they are actuated only when the stair climber is standing at the next stair edge upward. Only then is the drive source activated for the next climbing lift.
Other sensors measure the upper and lower end position of the flap, the lift frame or the foot elements. In this way, it is ensured that each lift step, whether up or down the stairs, starts from a defined position of the lift mechanism and ends at a defined position.
The proper process control of all drives, i.e. the lift mechanism on the stair climber, the drive on the support device and, where applicable, the drive between the stair climber and the support device, is best ensured by a microprocessor.